[Metrology] Caliper Adjustment

RV-N8ZG

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Jan 17, 2017
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I have a MBI Helios 5332-6 dial caliper that reads 0.0425" with the anvils closed.
the dial bezel is fixed, and there are no adjustments that I can find.
So far, Google has not been helpful...
Anybody have any suggestions for correcting the reading?

Neal
 
The gearing may have jumped a tooth or two. That is fairly common. Hopefully all the teeth are OK. Helios made some great tools. Dial calipers are delicate compared to vernier or digital versions.
 
All the dial calipers I've had were adjusted by inserting a straightened paperclip just under the rack gear and pushing the moveable jaw into the end of it to separate the pinion gear from the rack and moving the jaw forward a bit. The pinion gears have always been on a spring arrangement under the dial.
 
It's common for calipers to jump a geared tooth or two? I've never seen it myself, but it does happen. There may be DIY repair info on the web.

On many dial calipers, there is a tension spring that prevents backlash. I don't know how Helios calipers were made but if they're like Etalon, it would take prying open the case and possibly destroying the holders.

According to LIIS> http://longislandindicator.com/p11.html
Helios dial calipers are a brand made in Germany currently owned by Mahr. Originally, they were copies of the Etalon calipers. Several models are available in the US market from Fred Fowler Company, among others.

  • Sales: Fred Fowler Company for some models
  • Repairs: not possible on old models
  • Parts: not available
  • Information: search the web for Helios using the German language option
 
Yes it happens quite often especially where fine metal chips get onto the rack. Most of the good makers used to include a tool with a loop on the end similar to the opened paperclip. Ive got some old Helios in the shop, I'll take a look at them.
 
The Etalon and other Swiss made dial calipers come with a covered rack. Some calipers require that the crystal be removed to take them apart
and I read that the crystal has to be replaced. Parts for old Helios calipers are no longer available, so repair of worn or broken parts will be difficult.
 
On many dial calipers, there is a tension spring that prevents backlash. I don't know how Helios calipers were made but if they're like Etalon, it would take prying open the case and possibly destroying the holders.

Emilio -
Excellent input, thanks!

A little gingerly probing with a bobbypin has it back to close enough...

caliper.jpg
 
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